Since air travel became commonplace, the specter of dangerous blood clots has loomed over long-haul flights. For years, travelers have been bombarded with warnings about this risk, often accompanied by the suggestion to wear Travel Compression Socks. But is this advice essential, or just another travel myth?
The truth about travel compression socks is more nuanced than you might think.
“Using them is absolutely okay,” confirms Dr. Joshua Beckman, a leading expert in vascular medicine at UT Southwestern Medical Center in Dallas. However, he points out that current scientific understanding can’t definitively quantify exactly how much benefit they provide to travelers.
Travel compression socks, also known as graduated compression socks or stockings, are designed to apply pressure strongest at the ankle, gradually decreasing as they move up the leg. This graduated compression is intended to encourage healthy blood flow, aiding the blood in your legs to return to your heart more efficiently.
To understand the concern, it’s important to know about Deep Vein Thrombosis (DVT). In the United States alone, an estimated 666,000 individuals were hospitalized with DVT in 2020, according to the latest data from the American Heart Association. DVT occurs when a blood clot develops in a deep vein, typically in the leg. Furthermore, 432,000 people were hospitalized for pulmonary embolism, a condition where a clot travels to the lungs. Collectively, DVT and pulmonary embolism are known as venous thromboembolism (VTE), and in 2021, VTE was implicated in nearly 81,000 deaths.
Symptoms of DVT can include pain, swelling, and warmth in the affected leg. Pulmonary embolism can manifest as shortness of breath, coughing, and chest pain.
Studies show that long-distance flights can increase the likelihood of VTE by 1.5 to four times, according to a comprehensive review from the Cochrane Database of Systematic Reviews (updated in 2021).
Despite this increased risk, it’s crucial to remember that the absolute risk of developing dangerous blood clots from flying remains low. A 2007 study review in the Journal of Internal Medicine estimated only 4.8 cases of severe pulmonary embolism per million flights exceeding 12 hours. For flights lasting at least four hours, the risk of DVT within four weeks was estimated at 1 in 4,600 flights.
Dr. Eri Fukaya, a vascular medicine expert at Stanford University in California, explains that flying can create “a perfect storm” for clot formation. However, she emphasizes that individual risk factors play a much larger role.
Woman preparing for a flight by putting on travel compression socks to reduce the risk of blood clots.
Individuals at higher risk of VTE include older adults, smokers, those with obesity, and those with a family history of blood clots. Prior VTE sufferers, recent cancer patients, and individuals taking estrogen are also at increased risk.
Dr. Fukaya uses an analogy of a bucket to describe risk factors. People with pre-existing risk factors have a bucket that’s already partially full. Air travel, with its associated immobility and dehydration, might be the factor that causes the bucket to overflow, leading to a blood clot.
Prolonged immobility, inherent in long flights with cramped seating, is a significant risk factor. Furthermore, travelers may intentionally reduce water intake to avoid frequent bathroom trips, leading to dehydration, which can thicken the blood and further increase clot risk.
However, Dr. Beckman reiterates that the baseline risk of developing blood clots solely due to flying is so minimal that conducting definitive studies on preventative measures, like travel compression socks, becomes exceptionally challenging.
He references a 2022 study published in the American Journal of Obstetrics and Gynecology: Maternal-Fetal Medicine, which examined VTE risk in a high-risk group: pregnant and postpartum women. While women who flew showed a slightly elevated risk compared to non-flyers, the absolute difference was “very tiny,” 0.07% versus 0.05%, respectively.
These minute differences highlight the difficulty in proving the effectiveness of travel compression socks in preventing blood clots in air travelers. “If the risk is already very low, reducing it even further becomes statistically hard to measure, requiring an impractically large study group,” Beckman explains.
The Cochrane review, analyzing data from 2,918 participants across 12 clinical trials, found strong evidence that travel compression stockings significantly reduced the risk of asymptomatic DVT during flights longer than four hours. However, the review couldn’t draw conclusions about their impact on mortality, pulmonary embolism, or symptomatic DVT because these severe outcomes were absent in the study participants.
Current guidelines from the American Society of Hematology do not universally recommend travel compression socks. They advise against them for low-risk travelers on short flights and suggest considering them for longer flights only for individuals identified as high-risk for blood clots.
Studies in hospital settings have demonstrated the effectiveness of compression socks in preventing blood clots in post-surgical patients, according to Dr. Beckman. However, their benefit for non-surgical patients on bed rest is less conclusive. He argues, “If establishing benefit is challenging even for sick, bedridden hospital patients, proving benefit for healthy, mobile individuals traveling by plane or car becomes even more difficult.”
Despite the limited definitive scientific evidence for travel compression socks in healthy travelers, both experts agree that they are not harmful. Dr. Beckman states that if a physician recommends compression socks for any reason, it’s crucial to follow that advice.
For travelers concerned about blood clots, Dr. Beckman’s primary recommendation is simple and effective: “Get up and walk around every couple of hours. Stay well-hydrated by drinking plenty of water.”
Dr. Fukaya concurs and adds practical in-seat exercises: “While seated, regularly flex your calf muscles and rotate your ankles in large circles, both clockwise and counter-clockwise. When possible, remove your shoes and wiggle your toes. These simple movements significantly promote blood circulation.”
And for those who are already using and benefiting from travel compression socks? Don’t discard them just yet.
Dr. Fukaya, unlike Dr. Beckman, is a personal advocate for compression socks and wears them regularly. “Compression therapy has ancient roots,” she notes. “These socks stimulate calf muscles with movement and can effectively reduce leg swelling.”
“I wear them almost daily,” Dr. Fukaya shares, explaining that she initially started wearing them to better understand her patients’ experiences and discovered firsthand that “my legs simply feel much better when I wear them.”
While generally safe, Dr. Fukaya advises caution for individuals with poor circulation due to peripheral artery disease. However, for most people, experimenting with travel compression socks to find what works best is safe.
The market offers a wide variety of compression socks, from those marketed towards athletes to medical-grade options. Medical-grade socks are categorized by pressure levels (millimeters of mercury), but Dr. Fukaya finds these ratings less critical for travelers. “The actual pressure varies depending on individual leg size, and sock ratings lack standardization,” she explains.
She likens choosing compression sock strength to ordering food spice levels: “It’s like choosing ‘mild, medium, or spicy’ at a restaurant.” She recommends starting with a medium compression level and adjusting based on comfort and perceived benefit.
“You can even try wearing a sock on one leg and not the other during travel to compare how your legs feel afterward,” she suggests. Dr. Fukaya recommends knee-high socks over thigh-high versions. She cautions against rolling down knee-high socks if they are slightly too long, as this can create a tourniquet effect.
Ultimately, Dr. Beckman concludes that travel compression socks are perfectly acceptable for those who find them comfortable and beneficial. However, he emphasizes that focusing on overall health and well-being during travel includes more critical aspects, like sun protection.
“Travelers have numerous health considerations,” he points out. “It’s equally important to reassure them not to overthink aspects that are of minimal concern.” Prioritizing movement, hydration, and awareness of individual risk factors remain the most impactful strategies for safe and healthy air travel.
